**A. 3 min**

B. 4 min

C. 3.7 min

D. 3.2 min

**Solution:**

\[\left. \begin{array} { l } { \text { Total distance covered } = ( \frac { 7 } { 2 } + \frac { 1 } { 4 } ) \text { miles } } \\ { \qquad = \frac { 15 } { 4 } \text { miles. } } \\ { \therefore \text { Time taken } = ( \frac { 15 } { 4 \times 75 } ) \text { hrs } } \\ { = \frac { 1 } { 20 } \text { hrs } } \\ { = ( \frac { 1 } { 20 } \times 60 ) \text { min. } } \\ { = 3 \text { min. } } \end{array} \right.\]